Pruritus is an unpleasant sensation which provokes the desire to scratch.
Causes / risk factors
- Allergies
- Renal – chronic renal failure
- Hepatic disease – primary biliary cirrhosis, cholestasis, hepatitis
- Drug induced
- Haematological – lymphoma, leukaemia, myeloma, polycythaemia rubra vera, iron deficiency, mastocytosis
- Endocrine – hyperthyroidism, hypothyroidism, carcinoid, diabetes mellitus
- Dermatological – eczema, psoriasis, Paraneoplastic
- Parasitic – scabies, fleas
- Psychiatric – psychosis
Management
Correct the correctable
Review the patient’s medication. If an opioid has been recently prescribed consider opioid rotation. If a drug is the likely cause it should be stopped if possible. If there is cholestasis consider whether bile duct stenting is possible / appropriate?
Non drug treatment.
- Avoid provocative factors e.g. overheating, vasodilators
- Try to break itch/scratch cycle – clip nails short, wear cotton gloves.
Avoid washing with soap and bubble bath; add a handful of sodium bicarbonate to a cool bath. Pat rather than rub dry.
Drug treatment
Topical
Virtually all patients with pruritus and advanced cancer have dry skin. Rehydration of the skin with emollient cream may obviate the need for specific systemic treatments in some patients
- Use emulsifying ointment as a soap substitute and bath emollient e.g. Oilatum or Balneum
Use emollient after bathing e.g. Aqueous cream or Diprobase cream. Apply surface cooling agents with emollients e.g. 1% Menthol in Aqueous cream or Calamine lotion BP
Systemic
• Corticosteroid Useful if skin is inflamed but not infected eg
Prednisolone 10-20mg od PO
Dexamethasone 4mg od PO
Hodgkin’s lymphoma – 1st line
Sedating antihistamines Useful to determine whether antihistamine is of benefit e.g.
Chlorphenamine 4mg qds PO
• Non-sedating antihistamines Useful for maintenance treatment where antihistamine is helpful
e.g. cetirizine hydrochloride 10mg od PO
• NSAID Useful in en cuirass breast cancer with local pruritus
• Paroxetine 1st line in paraneoplastic pruritus. Also useful in cholestasis
polycythaemia vera and pruritus of unknown cause. Dose 5- 20mg od PO
• Mirtazapine 2nd line for paraneoplastic pruritus or where cause unknown
Also useful for Hodgkin’s lymphoma.
Dose 15-30mg nocte PO
• Ondansetron Useful in cholestatic pruritus
e.g. Ondansetron 4mg bd PO or 8mg/24hr CSCI
• Rifampicin Useful in cholestatic pruritus
Dose 150mg bd PO
• Cimetidine 2nd line in Hodgkin’s lymphoma. Dose 800mg /24hr PO
• Cholestyramine Unpalatable + causes diarrhoea, therefore not used 1st line
Dose 6-8g/24hr PO
• Intractable itch Benzodiazepine e.g. Diazepam 2mg tds PO
Chlorpromazine 25–50 mg nocte PO or
Levomepromazine 12.5–50mg /24 hrs CSCI
• Gabapentin for neuropathic irritation that may result in itch
• Naltrexone Oral opioid antagonist:used in some centres for uraemic or
cholestatic itch. Should not be used by patients taking opioids for pain control. Dose 12.5-50mg od PO
References
1. Lowitt M, Bernhard J. Pruritus. Seminars in Neurology 1992; 12: 374-84
2. Krajnik M, Zylicz Z. Understanding pruritus in systemic disease. Journal of Pain and Symptom
Management 2001;21:151-168
3. Zylicz Z et al. Paroxetine in the treatment of severe non-dermatological pruritus: a randomised controlled trial. Journal of Pain and Symptom Management 2003;26:1105-1112
4. Zylicz z et al. Paroxetine for pruritus in advanced cancer. Journal of Pain and Symptom Management 1998; 16: 121-4
Davis M, Frandsen J et al. Mirtazapine for pruritus. Journal of Pain and Symptom Management 2003;25:288-291
5. Raderer M et al.Ondansetron for cholestatic jaundice due to cholestasis. New England Journal Medicine 1994;300: 1540